Fluid compressor



Feb. 19; 1935. N. HERZMARK FLUID COMPRESSOR F' a Nov. 14,- 931 Sheets-Sheet l .INVENTOR Feb. 19, 1935. N.' HERZMARK f FLUID COMPRESSOR Patented Feb. 19, 1935 UN1TED lsrAila-s 'PATENT OFFICEl vApplication November 14, 1931, Serial No. 575,099 vIn Great Britain November 18, 1930 11 claims. (ci. 23o-112) This'invention has reference to iluid compressors ofthe kind comprising a cylinder mounted in a casing with a compressor-piston adapted to be reciprocated in the cylinder, and is more particularly intended for' compressingl air to be' stored in containers for operating engine turning gear' on automobiles, but capable also of use for tire inflating, paint spraying and other purposes.

One object of the present invention is to maintain the piston of the compressor in a rectilinear path so as to prevent undue friction and wear in the cylinder. Other objects of the inventionare to provide a high speed compressor, to prevent the undue heating of the cylinder head, to provide af pre-compression of the fluid to be conr-l pressed, to eliminatethe dead space at the head of the cylinder by means of an oil layer, to' allow the-piston to work idly when the pressure in the container has reached a predetermined degree and to lubricate the piston in the cylinderin a particular manner.

According to the present invention, the'piston.

of the Acompressor on its non-working stroke in the cylinder causes a pre-compression of Iiiuid in a chamber in prolongation of the cylinder, this pre-compressed fluid being caused to enter 'the cylinder before the commencement vof the working stroke of the piston within the cylinder. Oil

from the chamber is carried with the precom pressed air into the cylinder and forms a seal or layer around the head of the cylinder toeliminate dead space and to cool the head of the cylinder. 'I'he piston is provided .with a crosshead frame -member of a transverse length greater than the stroke of the piston, and travelling in guides within the compressor casing, so that the reciprocating movements of the piston Vin its cyllnder are steadied by the cross-head frame-member. Said arrangement makes it possible to provide a 'certain play between the piston and the cylinder, While allowing said piston to always remain concentric with said cylinder. Fluid tightness is obtained by means of the oil which is maintained ony the piston" by the grooves provided in the latter. The cylinder is mounted in the compressor casing in such a manner that its lower end depends into a chamber in the interior of the casing and such dependent portion is provided with oppositely arranged ports level with the top of the piston when the latter is at the bottom of its stroke, these ports communicating with the chamber in the casing. The pre-compressed fluid passes from the chamber to the cylinder through these ports whenthe latter are uncovered. The head oi the cylinder is provided able for a compressed air valve stem` i.

with a valve which when open delivers to a container for the compressed fluid, so that such iluid compressed in the cylinder during the upward movement of the piston; will be forced through the valve to the container; this valve is so constructed that when the back pressure in the container is sulciently great, the valve will be putout of action.

The invention is hereafter described with reference to the accompanying drawings, in which: 10

Figs. 1 and 2 are sectional elevations, at right angles to one another, of an air compressor suitstarter for an explosion engine.

1 Figure 3 is a section on the line A-B of Fig. 1 and Fig. 4 is a plan view of the compressor represented in Fig. 2.

Fig. 5 is a detail view in section, upon a larger v scale. o

The casing a oi' the'compressor comprises a sump portion b, and' air chamber c and a head portion d. It is provided also with an air inlet valve e, a cylinder f dependent from the head d into the air chamber c and with suitable ball or similar bearings g g for a driving crankshaft h having a crank 'pin h1. Figs. 2 and 4 show the casing a provided with end plates carrying the shaft bearings, detahably secured upon the cen-l tral portion by bolts and nuts a1. The air chamber c is provided with parallel guiding face plates c1 c2 secured on the inner wall of the casing a' by screws c3. f

In the head'f1 of thecylinder f'is arranged a delivery valve shown in the form of a ball i, said ball beingvmounted in a hollow'mushroom valve` a' held to its seating il in the head of the cylinder by a spring 1' which bears against a washer 7'3 secured by a cotter on the upper end of the hollow An adjustablehstop` pini1 is arranged above the ball i to limit the lift of the latter. f

The cylinder f is formed with ports f2 f2 located exactly above the level of the top of the piston 1c when the piston is at the lower end of its stroke (see Fig. 1), in which position these ports allow communicationA betweenA theair chamber c and the interior of the cylinder f. l

When the ball is lifted from its seat in the valve :i by the pressure of air compressed in the cylinder j, the air passes through the center of the valve head to the interior oi' the hollow stem y and thence by a suitable passage i2 and pipe i3 to a container i4. When however the mushroom valve i is moved from its seating i1 as hereafter explained, the air contained in cylinder f and forced lower part of crank pin h1 a clearance space may 2 up by the piston k will pass by the seating 9'1 (and not pass the ball i), thus circulating idly through a passage d1 leading to. a channel d2 which delivers back to the air chamber c.

Mounted upon the crank pin h1 by means of a bush or die ic with sliding` engagement, is a cross-head k1 forming part of the piston k but of a transverse length considerably greater than the stroke of the piston k. This cross-head k1 is shown secured by studs lca to a U-shaped frame-member k3, the outer walls of which bear against the parallel face plates c1 c, and the which engages slidingly with the bottom of the bush or die k0 on the crankshaft. As the piston Ic rises and falls, due to the motion of the bush or die on the frame-member k3 is guided by the plates cl so that the piston Ic is steadied and kept in a truly rectilinear path.

The lower part of the frame-member k3 is also provided with a dipper lc4 which enters a well or recess b1 in the sump b. 'I'his dipper k* is provided with an annular flanged or similar foot kf', which serves to splash up the oil collected in the well h1.

The head portion d of the casing a is shown provided with a detachable cap d3 screwed upon a ferrule itself screwed into said head portion, to allow of the fitting of the cylinder ,f in place, the cylinder being retained by means of its outward ange f3 resting on a shoulder d4 in the head, and of the valves i and i with their accessories, and also to allow of subsequent access to these parts. i

The sump b being filled with relatively thick oil, for example, castor oil, the rotation of the will cause the piston It and crossliead frame-member k1 k3 to reciprocate together, moving respectively in the cylinder f and between the guiding face plates c1 c2. As the crank pinl rotates, the bush k moves from side to side ofthe frame-member k3 which it will be noted is bathed with oil; by this construction,

be provided between piston k and cylinder f without theY piston ceasing,

in its rectilinear displacement, to be concentricwith said cylinder. Fluid., tightness is insured by the oil, which is not given time enough to flow out due to the braking action produced by grooves f4. As the piston 1c rises, it forces compressed air past the ball valve i and through the port i2 into the container allows the valve i to close and creates a fall in pressure in` the cylinder f sufcient to produce a suction on the valve i strong enough to draw the mushroom head thereof away from seat i1, thereby permitting the idle circulation of air into the passages d1 and d2 and back to the air chamber c, as hereinbefore suggested. 'I'his suction action continues during the major portion of the down stroke, and in fact until the piston reaches the level of the ports f2 f2. As the piston rises, the suction produced in the chamber c draws in air through the valve e; this air is subjected to a preliminary compression in the chamber c during the return movement of the piston by reason of the fact that (as will be noted from Figs. 2 and 3) the capacity of the free annular space in the chamber c is relatively small as compared with the displacement in the piston k. There is thus provided a decrease in volume and a corresponding increase in pressure of the air previously the valve e. Also, on the downward stroke, valve c is closed by reason of this increased pressure in v cylinder.

the rotating crankshaft h,

i4. When the piston descends, it

admitted to the chamber c through the chamber c.- The continued downward move'- ment of the piston lc finally uncovers the ports f2 ,f2 whereupon the partial vacuum is relieved by a rush of air from the chamber c into the At the Sametime, the descent of the frame-member k3 into the lower part of the air chamber c displaces the air upwardly. This air, which has been slightly pre-compressed in the chamber e, is subsequently compressed to the full extent by the upward movement of the piston, during which the supply of air in the chamber c is' replenished through valve e. Meanwhile the dipper k:4 has entered the well or recess b1 in the sump and has splashed up the oil, which, .as the `operation continues, not only maintains the lubrication of the crank pin h1, cross-head frame-member k1 7c3 and piston Ic, but impregnates the air in the chamber o so that oil passes with the air through the ports f2 f2 into the cylinthe cylinder is kept comparatively cool, while the compressed air forced into the container also loses heat by expansion.

The pipe delivers to the container i4 below the level of a bath of oil i5 in said container so that the oil is subjected to the pressure of compressed air stored in the container. When the pressure above the oil `reaches a predetermined degree, oil is forced back along the pipe i3 to passage i2 and to the interior of the head d where it bears upon the upper end of the mushroom valve 7'; when the oil pressure is sufcient to overcome the valve spring i2, it forces the valve y oi its seat 71 so that the piston no longer passes air through the ball valve i. Any air driven forward by the piston will pass through the valve seating 71 into the passage d1; along-channel d2 back to the chamber c.-

The channel d2 is shown closed at top by a screw plug d5 for manufacturing purposes: the sump b can be filled up with oil by removing the inlet valve e. A lateral passage d6 from the interior of the head d and parallel with passage d1 communicates with the channel d1l by way vof a. needle valve d" which can be screwed back to allow the return of superfluous oil from the interior of the cap d3 to th sump b, and also to replenish the sump by returning surplus oil from the container.

In order to insure a proper air tight seal between the piston k and the Wall of the cylinder without the use of piston rings, the piston is grooved as shown in Fig.\5. A peripheral gutter f4 is formed with an inwardly curved wall f5 above the gutter to catch any oil which may leak from the top of the piston down between the piston and cylinder wall and such oil owing to its viscosity and noncompressible nature is scraped off the wall by the gutter f4 to form upstanding beads as at f6, which spread outwardly during *movement of the piston and seal the joint. Four of these gutters f4 are indicated in Fig. 1.

The amount of oil splashed up from the sump b by the dipper lc4 can be regulated by altering the diameter of the foot h5 of the dipper. This foot may be reduced in diameter or made adjustable in any manner desired.

Althoughdescribed and shown in its applicamade in the construction, form and disposition of the parts without departing'from the principle of my invention as comprehended Within the scope of the appended claims.

What I claim is:

l. A fluid compressor of the type described, comprising in combination, a casing, a cylinder in said casing, a piston adapted to reciprocate in said cylinder, driving/means for actuating said piston, a chamber in line with said cylinder, means operatively connected to said driving means for precompressing air in said chamber prior to iinal compression thereof in said cylinder, said cylinder being provided with ports connected with said chamber and-opening into said cylinder in such a position as to be uncovered by said piston at the end ofthe non-working stroke thereof. A

. 2. A fluid compressor .of the type described,

comprising in combination, a casing, a vertical cylinder in said casing, a piston adapted to reciprocate in said cylinder, driving means for actuating saidpiston, a chamber in said casing located below said cylinder in line therewith and` adapted to contain said driving means and the outer part of the piston, whereby air is precompressed in said chamber during the downward stroke of the piston, said cylinder being provided with ports connected with said chamberA and opening into said cylinder at points level with the top of said piston when the latter 4is at the bottom of its stroke, the lower end of said chamber being y adapted to contain oil, means operatively connected with said driving means for splashing said oil,I whereby oil from the chamber is carried with the precompressed air through said ports into said cylinder and forms a seal or layer around the head of the cylinder\to eliminate. dead space and to cool the head of said cylinder, means for admitting air into said chamber during the upward stroke of said piston, a receiver for'the compressed air, and means for allowing air to flow from said cylinder into said receiver during the upward stroke of said piston.

3. A fluid compressor ofthe type described, comprising in combination, a casing, Aa vertical cylinderI in said casing, a piston adapted to reciprocate in said cylinder, a chamber in said casing located below said cylinder and in line therewith,

- two vertical parallel guiding plates in said chamber placed at a distance from one another substantially greater than the stroke of the piston,

a cross-head frame-member rigidly connected to saidpiston and adapted to slide between said guiding plates, driving means for actuating said cross-head, whereby air is precompressed in said chamber during the downward stroke of the piston, said cylinder being provided with ports connected with said chamber and opening into said cylinder at points level with the top of said piston when the latter is at the bottom of its stroke,

. the lower end of said chamber being adapted to A contain oil, means for admitting air into said chamber during the upward stroke of said piston, a receiver for the compressed air, and means for allowing air to ow from said cylinder into said comprising in combination, a casing. a vertical cylinder in said casing, a piston adapted to reciprocate in said cylinder, a chambervin said casing located below said cylinder and in line therewith, two vertical parallel guiding plates in said chamber placed at a distance from one another substantially greater than the stroke of the piston, a cross-head frame-member rigidly connected to said piston and adapted to slide between said guiding plates, driving means for actuating said cross-head, whereby airis precompressed in said chamber during the downward stroke of the piston, said cylinder being provided with ports connected with said chamber and opening into said cylinder at points level with the top of said piston when the latter is at the bottom of itsstroke, the

lower end of said chamber being adapted to conl I tain oil, means operatively connected-with said driving means for splashing said oil, whereby oil- 'the cylinder to eliminate dead space and to cool the head of saidcylinder, means for admitting air into said chamber during the upward stroke of said piston, a receiver for the compressedair, and means for allowing air to dow from said cylinder into said receiver during the upward stroke of the piston. l

5. A iiuid compressor of the type described, comprising in combination, a casing, a vertical cylinder in said casing, a piston adapted to reciprocate in said cylinder, a chamber in said casing located below said cylinder in line therewith, the lower end of said .cylinder depending into said chamber, driving means for reciprocating said piston in said cylinder located in said chamber, whereby air is precompressed in said chamber during the downward stroke of the piston, the lower part of said cylinder which projects into said chamber being provided with ports opening into said cylinder at points level with the top of said cylinder when the latter is at the bottom of its downward stroke,l a spring seated valve opening in the inward direction for connecting said chamber with the atmosphere whereby airis admitted into said chamber during the upward stroke of said piston, a receiver for the compressed air, and a valve at the upper end of said cylinder for allowing air to flow from said cylinder into said receiver during the upward stroke o! said piston.

6. A'iluid compressor according to claim 5 in which the' lower part of said chamber is adapted to contain oil, further comprising means operatively connected to said driving meansl for splashing said oil'in'the said chamber, whereby oil from said chamber is carried with the precompressed air through said ports into said cylinder and forms a seal or layer around the head of the cylinder so as to eliminate dead space and to cool the head of said cylinder.v

7. A iluid compressor according to claim 3, in which the means for admitting air into said chamber consists of a spring seated valve opening inwardly, and the means f or allowing air to ilow from said cylinder to said receiver consists of a valve, further comprising means operative by the back pressure in said receiver, adapted to directly connect the upper end of said cylinder with, said chamber when said back vpressure exceeds a predetermined value.

84A fluid compressor according to claim 3, in l which the means for allowing air to iiow from said cylinder to said receiver, comprise, a valve seat provided in the inner face of the cylinder head, a mushroom valve adapted to cooperate with said seat, a conduit for connecting the inner face of said valve with the chamber, a stem on said valle extending throughout the cylinder head, said stem being provided with a longitudinal conduit extending throughout its length, a'bali valve` disposed in the last mentioned conduit so as to a1- low the air to flow outwardly and to prevent it from fiowing inwardly, and a spring for operating said mushroom valve on 'its seat.

9. A iiuid compressor according to claim 3, iurther comprising an oil chamber located above said cylinderhead, and a pipe for connecting said oil chamber to said receiver, in which a certain quantity of oil is present at the bottom of said receiver, the means for allowing air 'to flow from said cylinder to said receiver comprising, a valve seat provided in the inner face of the cylinder head, a mushroom valve adapted to cooperate with said seat, a conduit for connecting said valve seat with the air chamber, a stemon said valve extending throughout said cylinder head into said oil chamber, said stem being provided with a longitudinal conduit extending throughout its length, a ball valve disposed in the last mentioned conduit so as to allow air to ow outwardly toward said receiver and to prevent oil from ilowing into said cylinder, and a spring for applying said mushroom valve on its seat, whereby said spring is flattened when the pressure in thereceiver exceeds a predetermined value, so that the top of the cylinder is then directly connected to the air chamber and the compressor force air into the receiver.

l0. A iluid compressor of the type described, comprising in combination, a casing, a vertical cylinder in said casing, a piston adaptedvto. reciprocate in said cylinder, a chamber in said casing located below said cylinder and in line thereceases to with, two vertical parallel guiding plates in said. chamber placed at a distance from each other ton when the latter is at the bottom of its stroke, means for admitting air into said chamber during the upward stroke of said piston, a receiver for the compressed air and means for allowing air to flow from said cylinder into said receiver during the upward stroke of said piston. 11. A iluid compressor'accordng to claim 10 in which the lower part of said chamber is adapted to contain oil, further comprising a dipper integral with the lower part of said cross head adapted to splash said oil, whereby oil from said chamber is carried with the air into said cylinder, in order to eliminate dead space and to cool the head of the cylinder.

. `NICOLAS', HERZMARK. 

